In U.S. heart failure is a major public health problem whose management consumes about 1% of the national health care resources. Approximately 3 to 4 million Americans were afflicted by heart failure, with 400,000 new cases being diagnosed each year. Heart transplantation has been the most effective therapy as compared to other medical treatments. Nevertheless, cardiac transplantation remained limited by the complications of long-term immunosuppressive therapy, allograft coronary artery diseases, and most critically, the serious shortage of donors. The annual number, of donor heart remains much constantly around 2,000. However, the patients who are qualified to receive donor heart are estimated to be 16,500 annually.
Mechanical circulation support (MCS) systems, both total artificial heart (TAH) and ventricular assist device (VAD) have been intensively studied, hoping to replace the role of heart transplantation for end-stage heart failure patients. Left ventricular assist device (LVAD) is versatile in providing heart failure patients. With therapies including bridge to transplantation, bridge to recovery and alternative to transplantation. The large-scale REMATCH (Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure) trial, which involved 19 medical centers and 129 end-stage heart failure patients, indicates that, for patients treated by LVAD or pharmacologic therapy, one-year survival rate of the LVAD group doubles that of the pharmacologic group. Moreover, LVAD group enjoys much better quality of life during the period of support. It has been an accepted fact in cardiology society that a total implantable long-term (3-5 years) mechanical circulation support device, in particular the LVAD, will solve the current dilemma of donor shortage for the heart failure patients.
LVADs have been developed in recent years into a new medical modality that is expected to either work as a short-term bridge-to-transplantation support or replace in a long-term manner as an alternative of heart transplantation. Continuous flow LVADs are smaller but thrombogenic, and the non-pulsatile circulation support may induce many complications in micro-circulation in end organs when used chronically. Pulsatile LVADs are more physiologically compatible, but the bulkiness and larger energy consumption prevents them from being widely adopted.
An ideal mechanical circulation support (MCS) design should possess, but not limited to, the following characteristics: it 1) provides sufficient and adaptive cardiac support according to various physiological conditions or therapeutic requirements, 2) avoids blood trauma and device-induced complications, 3) requires simple implantation procedure and post-operational care, and 4) guarantees safety operation and allows emergent salvage including necessary device maintenance/repair or replacement. To date, none of the leading-edge LVAD products can meet all these requirements.